The instant invention relates to a gas dryer having an outlet chamber that is connected to a pressure relief space by an outlet valve. The gas dryer is capable of removing moisture from gas that flows therein.
A gas dryer of this type operating with air as gas is known from FIGS. 2 and 3 of the article "Lufttrockner" (which means air dryer) on the pages 31 through 33 of the WABCO-publication "Aus unserer Entwicklung 1983" (which means "From our development 1983"). This air dryer functions according to the known adsorption principle. In the outlet chamber of this air dryer there accumulates condensation. In regeneration phases of the known dryer, the outlet valve which controls the connection between the outlet chamber and an outflow to the atmosphere is opened, so that the condensation accumulated is able to escape from the outlet chamber in these phases. Additionally, the regeneration gas stream which is due to the work principle of this air dryer can escape through the outlet chamber and the outflow in these phases. The atmosphere serves as pressure relief space in this case. The piston that actuates the outlet valve is subjected to the pressure in the control chamber in the opening direction of the outlet valve. That pressure is fed to the control chamber in idling phases of the compressor from a dried air pressure reservoir via a control line, a pressure regulating member and a control connection of the dryer. The control line and the control chamber form a dead end for the pressure medium that has entered into them so that water that may have entered the control line and the control chamber with the pressure medium may settle in the line and in the chamber. This water may originate from residual moisture of the pressure means, in particular as a result of malfunctions and/or critical operating states. This water may result in corrosion. This water may also freeze and thereby block the control line and/or the piston of the outlet valve, thus preventing the opening of the same.
Any of the above mentioned conditions may result in serious malfunctions and even in the failure of the gas dryer and/or cause serious malfunctions in the consumption devices located downstream of the gas dryer.